An aqueous solution of a salt is known as brine. The salt is:
Sodium chloride
Understanding What Brine Is
The term "brine" is commonly used in chemistry and everyday life to refer to a specific type of aqueous solution. An aqueous solution means a solution where water is the solvent.
While many salts can dissolve in water to form aqueous solutions, the term "brine" specifically refers to an aqueous solution of sodium chloride ($\text{NaCl}$). It is essentially a concentrated solution of common table salt in water.
Identifying the Salt in Brine
Let's look at the options provided:
- Sodium chloride ($\text{NaCl}$): This is common table salt.
- Potassium chloride ($\text{KCl}$): This is another type of salt, sometimes used as a salt substitute.
- Calcium chloride ($\text{CaCl}_2$): This is a salt often used as a drying agent or for de-icing roads.
- Sodium nitrate ($\text{NaNO}_3$): This is a salt used in fertilizers and explosives.
By definition and common usage, brine is synonymous with a strong solution of sodium chloride in water. While the other salts also form aqueous solutions, they are not typically referred to as brine. For example, a solution of potassium chloride in water would be called an aqueous solution of potassium chloride, not brine.
Therefore, the salt present in brine is sodium chloride.
Comparing Common Salts
| Salt | Chemical Formula | Common Name/Usage | Referred to as Brine? |
|---|---|---|---|
| Sodium chloride | $\text{NaCl}$ | Table salt, Rock salt | Yes (when in aqueous solution) |
| Potassium chloride | $\text{KCl}$ | Salt substitute, Fertilizer | No |
| Calcium chloride | $\text{CaCl}_2$ | De-icer, Drying agent | No |
| Sodium nitrate | $\text{NaNO}_3$ | Fertilizer, Preservative | No |
This comparison clearly shows that sodium chloride is the specific salt whose aqueous solution is known as brine.
Summary
In the context of the question asking about the salt in an aqueous solution known as brine, the correct salt is sodium chloride. Brine is a term specifically reserved for concentrated solutions of $\text{NaCl}$ in water.
Revision Table: Brine Definition
| Term | Definition | Key Component |
|---|---|---|
| Aqueous Solution | A solution where water is the solvent. | Water |
| Brine | A concentrated aqueous solution of a specific salt. | Sodium chloride ($\text{NaCl}$) |
Additional Information on Brine and Salt Solutions
Brine is used in many applications, including:
- Food preservation (pickling, curing meats).
- Industrial processes (e.g., chlorine and sodium hydroxide production).
- Refrigeration systems.
- De-icing roads at lower concentrations than rock salt.
The concentration of sodium chloride in brine can vary, but it is typically higher than that of seawater (which is also an aqueous solution of $\text{NaCl}$ but at a lower concentration, around 3.5%). Saturated brine, where no more salt can dissolve, has a concentration of about 26% $\text{NaCl}$ by weight at room temperature.
Understanding the specific terminology in chemistry, like the term "brine," is important as it refers to a particular and widely recognized substance.
Important Questions from Chemistry in Everyday Life
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